Peculiarities of dissection of rat pericardium and study of its lymphoid component

Today, the structure of the medulla remains an important open question in immunomorphology: the morphological equivalents of the three main functional groups of lymphocytes of innate immunity have not yet been identified. The lack of clear morphological markers of these lymphocytes complicates the study of their localization, differentiation and functional activity within the medulla tissues. This issue creates a significant gap in modern ideas about the immune microorganism of the heart. It has been proven that representatives of nonspecific immunity play a certain physiological role in the functions of the parietal pericardium: γδ-T lymphocytes and B1 lymphocytes. However, their topography, morphology and dynamics of the number in the experiment and in pathology remain poorly studied. The aim of the study was: to develop and optimize the method of preparing the medulla of rats in order to provide access to the medulla without tissue damage; determination of the morphological characteristics of the lymphoid component of the medulla in laboratory rats; assessment of the localization and structure of lymphoid elements in the fibrous leaf of the medulla; study of the functional features of the lymphoid apparatus of the medulla under normal conditions as a basis for further comparisons in experimental models of heart pathologies, which can be used as reference values ​​in the study of experimental models of cardiovascular diseases. Research results. The following cellular composition was found in the medulla of white rats in the norm: macrophages, small lymphocytes, medium lymphocytes, broad-plasma lymphocytes, fibroblasts. The lymphoid tissue of the medulla is represented by diffuse lymphoid tissue and clusters of 5-8 lymphocytes forming clusters. The results obtained can serve as a morphological reference point for further experimental studies in the field of immunocardiology, in particular for the assessment of pathological changes in the medulla. Despite the presence of morphologically verified immunocompetent cells in the structure of the pericardium, the question of their functional activity, phenotypic diversity and role in maintaining immune balance both in physiological conditions and in pathology remains insufficiently studied.